Fluid pressure switch



April 18, 1933. F G HOBART FLUID PRESSURE SWITCH Filed Feb. 17, 1930 ATTORNEY Patented Apr. 18, 1933 UNITED STATES PATENT OFFICE FRANKLIN G. HOBART, OF BELOIT, WISCONSIN, ASSIGNOB 'IO FAIRBANKS, HORSE & 00., OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS FLUID PRESSURE SWITCH Application filed February 17, 1930. Serial No. 429,065.

This invention relates to improvements in fluid pressure switches, and particularly to mechanism for actuating electric switches responsively to fluctuations in fluid pressure.

An object of the present invention is to provide simple and effective switch actuating means which serve positively and quickly to close and open the electric circuit, and which practically prevents arcing and sparking across the switch contacts.

A further object is to provide an improved switch operating mechanism including means for self-lubricating certain portions of the mechanism to insure constant and low frictional resistance.

A still further object is to provide an improved pressure actuated switch which is neat and compact in arrangement, and is simple and economical to construct and main tain.

Further objects and advanta es will ap pear from the following detaile description of parts and the accompanying-drawing, in which:

Fig. 1 is a side elevation of a preferred form of pressure switch to which the present improvements are applied; Fig. 2 is a longitudinal section of the preferred switch shown in Fig. 1; Fig. 3 is a fragmentary section taken along the line 3-3 in Fig. 1; Fig. 4 is a diagrammatic showing of certain parts of the switch in the closed circuit position, and Fig. 5 is a diagrammatic showing of the parts of the switch illustrated in Fig. 4 but in the open position of the switch.

It will, of course, be understood that the present detailed description of parts and the accompanying drawing relate to a single preferred executional embodiment of the invention, and that substantial changes may be made in the detailed arrangement and construction of parts without departing from the spirit and full intended scope of the invention. I

Referring by numerals to the drawing, 10 designates a base support, having an inlet opening 11 for receiving a pipe (not shown) or the equivalent, leading from a reservoir, in which a fluid pressure is to be maintainedv between established limits. An orifice-forming member 12 is removably secured in the base 10 in communication with the opening 11, and slidably and freely movable in the orifice is a cleaner member 13 which is fixedly secured to a diaphragm 14. This cleaner member being movable in the orifice, insures a clean and unobstructed opening at all times. The diaphragm is secured in-pressure-tight relation between the base 10 and a'supporting member 15. As is, well known to those skilled in the art, the diaphragm is responsive to pressurefluctuations in the reservoir, and the movements of the diaphragm may be utilized to control the action of an electric switch.

A projection 16 is fixedly secured to the diaphragm oppositely to the orifice cleaner 13, and this projection engages a socket on a lever 17 which is pivotally secured to the support 15 by means of a pin 18. The lever 17 may be formed of a heavy sheet material of a substantially U shaped section, the lower or inner ends being inwardly directed and riveted in overlapping relation (Fig. 2). The movement of the lever under the influence of the diaphragm, is opposed'by a plurality of springs, as will hereinafter appear. A spring 19 is adjustably secured toa bridge portion 20 on the lever 17, while at its opposite end, this spring is fixedly secured to the supporting member 15. In the present, preferred example, it will be apparent that this spring opposes the outward pivotal movement ofthe lever, and therefore not only tends to depress the diaphragm, but also servesto maintain the lever 17 and the projection 16 in contact with each other. The downward movement of the lever 17 is limited by a stop member 21 which is provided on the support 15.

An arm 22 is pivotally secured by means of a pin 23 to the lever 17 and is disposed substantially at the outer end portion thereof. One end of the arm 22 is, by preference, provided with inclined surfaces 24 and 25, which meet at an edge or apex 26, the surfaces being inclined relatively to each other, so as to subtend an angle of substantially degrees. The arm 22 may be formed of substantially U shaped section, after the man ner of the lever 17 A spring 27 is adjustably secured to a bridge portion 28 of the arm 22, while the opposite end of this spring is secured to the overlapped connecting portion 29 on the lever 17. The outer end portion of the arm 22 is movable, under the influence of the'lever 17, incontact with a roller 30 which is carried in a guide slot 31 formed in a brush carrier 32 which is in turn pivotally secured to the support 15 by means of a pin 33. A crossunemberz34' tween the contactsand the operating mechanism, blocks a'nd 41 are provided between .the contacts and the actuating mechanism.

Theseblocks are formed of a suitable in- 'sulating material, and serve as electrical barriers between the stationary contacts and the switch mechanism. Additional members of insulating material, say in the form or tubes, may be employed where the lead wires extend through the members 10 and 15. The movement ofthe brushes, by a quick,

snap action, into or out ofengagement with rier is formed the contacts 37 results from a novel arrangement of'brush-actuating elements associated operatively with the lever 22. The roller30 is carried on a pin 42 (see Fig.3), which is mounted to rotate freely in bearings 43 and 44 formed, by preference,ofvwood or any other equivalent materiahwhich is impregnatedlwith a lubricant. By this provision, the pin 42 is, at all times, lubricated by the bearing material, to providea constant and low frictional resistance at these points. Annular grooved members 45 are attached to the bearings 43 and 44, and'these members are guldedby the slots 31, these slots being wider than the diameter ofmembers 45, to provide a lost motion engagement between the roller 30 and the carrier 32. The carof. a pair of spaced side mem bers, (F g. 3) engagingiopp0site sides of the support 15, the slots 31' being formed in'the opposite sides of the carrier. The .end portions of the slot 31 are provided with stop projections 46 and 47, inorderto limit the r'olling movement of the roller assembly in thelslot, and, further to impartthe desired rocking movement'to the carrier 32, as will hereinafter appear.

actuation of thebrush carrier and lever 22 may be clearly seen from Figs. 4

pin 18, which movement causes the arm 22 to pivot about itspin 23 to tension the spring 27, and also to cause the apexed end portion 26 of the arm 22 to ride upon the roller, Upon continuing this movement, the edge 26, in

contact with the roller 30, moves to a point where a line passing through the edge 26 and the center of the roller is substantially normal to the guide surface 31. Any-further movement ofthe lever causes the roller to move along the inside surface adjacent the slot 31 until it abuts the projection 46. This occurs :by asudden snap movement, caused, in part, by the edges 26 passing over the roller, and rolling along the surface 25 of the arm. This movement is rapid, because prior to this time, the spring 27 which holds the arm 22 into contact withthe roller isbeing loaded or tensioned, and therefore after the roller passes the edge of the arm, the roller rapidly moves alongthesurface 25. Both the impact caused bylateral movement of the loose bearing, and the leverage about the pin 33 coact to cause a quick make or break of the circuit, according to the direction of movement of the diaphragm. It will, of course, 7

be understood that in order to break the contact by oscillating the carrier to a position shown in Fig. 5, the above operations take place in the reverse order, with the same quick movement. 1

Rocking movement'of the carrier 32 n eitherdirection is limited by means of a pin 48 securely attached to the carrier, which coacts with the walls of an opening 49 formed in the support 15. It will be readily seen that the entire switch operating mechanism 1s supported by the member'15,'which also serves as a closure member'to seal the diaphragm in pressure tight relation to the base 10. 'Several distinct advantages are em,

bodied in" the present, preferred assembly, among them beingthe feature for maintain ing the brushes, positively inoperative during any'minor fluctuations of the operating mechanis'm, due to the effect of lesser fluid-pressure changes below the diaphragm. It willbe readily seen that due to the preferred ar tionary contacts 87. When the arm 22 starts to move over the roller, the spring 27 still has the same effect, and therefore there is no tendency for the brushes to leave their contact surfaces until the mechanism has been actuated to a point where the roller is permitted to move. Likewise it will be readily seen that the spring 27 acting through the arm 22 and on the roller 30, insures the same effect, that is to hold the brush and carrier inoperative during preliminary movements of the operating mechanism.

The switch operating mechanism described, provides unique and eflicient facilities for controlling the relative movement of the lever 17 and the arm 22. As will be noted particularly from Fig. 2, the spring 19 is adapted to be relatively heavily loaded, and is provided with a screw and nut adjustment at its point of anchorage with the lever 17, the lower or opposite end of this spring having a fixed anchorage onto the stationary member 15. In distinction from the spring 19, the spring 27 has one end fixedly anchored to the lower or cross portion of the lever 17 which operates, of course, as a movable member, the opposite end of spring 27 being adjustably anchored through the bolt and nut arrangement shown, to substantially the central portion of the arm 22. As a result of this arrangement, the resultant movement of lever 22 in effecting opening and closing movements of the switch, is influenced by both springs, an adjustment of either or both of which will determine the fluid pressure necessary to be applied to the diaphragm to open and close the switch and serve to vary the fluid pressure limits between which the switch opens and closes.

It will be noted that as the diaphragm is urged outwardly under the action of increased pressure, both of springs 19 and 27 are increased in load, and that the lighter spring 27 is again somewhat reduced in ten si on as soon as the parts are brought into the relation of Fig. 5, upon closing of the switch.

As will clearly appear from Fig. 2, the

' lever 22 although pivotally connected to lever 17 is nevertheless impelled positively in its movements across the axis of the roller 30. The rocking or vertical movement of lever 22 is, however, influenced more or less directly by the loading of spring 27, the major action of which occurs at times when the apex portion 26 passes from one side to the other of the roller 30. The major movement of spring 19 is due to, and follows almost directly, the movement of lever 17 about its pivot 18 under the influence of increase or reduction of fluid pressure as applied to the diaphragm.

It will be seen that due to the provision of separate adjustments for the springs 19 and 27 the action of the switch may be regulated within narrow limits to obtain any reasonable range of fluid pressures desiredin the system to which .the presentmechanism is "attached. It is, of course, presumed that in a dust-proof casing, (not shown).

I claim 1. In a switch, an actuating member, a lever 1 actuated thereby, a rotary thrust element 0peratively connecting the lever to said member, and means constituting a fibrous, oil retaining bearing surface for the thrust element.

2. In a switch, a stationary contact, a movable contact, a carrier for the movable contact, said carrier being in the form of a lever having an open, slotted endportion, a rotary member journaled in and freely. movable across said portion, a switch-actuatingparm havinga wedge shaped portion adapted to impinge upon said rotary member from either of the opposite sides of said lever, and a spring secured to said actuating arm.

3. In a switch mechanism, a brush, a fixed contact adapted to be engaged thereby, a lever constituting a brush carrier and pivoted between its ends, the lever having a slot near .one of its ends, a rotary thrust element journaled in lostqnotion relation in said slot, a member having a wedge shaped actuating portion for applying an actuating force to either side of said lever, through the thrust member, in a directionsubstantially transverse to the lever and a spring connected-to saidactuating portion and adapted to bias said actuating portion against ,said thrust member.

, 4:. In a switch mechanism, a lever, a member havinga wedge-shaped lever-actuating portion and a thrust member engaged by said wedge-shaped portion, and carried in floating relation, by the lever, said lever having a seat for said thrust member, of substantially greater width than the corresponding dimension of the thrust member.

5. In a switch mechanism, an actuating member, a member actuated thereby, a rotary element engaged by the actuating member and journaled in said actuated member, and 1' means forming a bearing of fibrous material, for said rotary element.

6. In a switch mechanism, a lever having a jaw portion near one of its ends, an arm having a wedge shaped end, and a member 5.

operable in said jaw portion and engaged by the wedgeend ofsaid arm, said memberbe ring of lesser width, than the Corresponding dimension of said jaw portion.

7. In a snap switch mechanism, an actuatingmember, an actuated member, arranged for oscillating movement, said actuated member having a slotted portion,and a roller carried by the actuated member, engaged by the actuating member and of a diameter less than the length of said slotted portion, being thereby adapted for movement in said slotted portion transversely andindependently of thecarrier andwithin its normal path of actuation.

' 8. In a switching device, a' switch actuating lever, a circuit controlling member, a rotary element carried by said member, and c means forming a non-metallic bearing for said rotary element.

9. In a switch, a pivoted lever, a pivoted switch-actuating arm having an edged portion, a springtending to urge the edged portion into operative position with respect to said lever, an abutment roller at the outer end of the lever, and disposed in the path of movement of the edged portion, and spaced abutments for the roller, carried by the lever, and spaced apart a distance greater than the diameter of the roller.

10. In a switch, a pivoted lever operatively connected to the switch, and including a pair of spaced, parallel side members, a pivot disposed between the ends of the lever in bridging relation to its side members, slotted guides formed near corresponding ends of the side members, a rotary thrust element disposed for movement along the slots in, said guides in bridging relation to the side mem- 40 hers, said element being of a diameter less than the length of said slots, adapted for ap plying an actuating force to either side of said lever, through the thrust element, in a direction substantially transverse to the lever.

11. In a snap switch structure, a snap-'impact member for connecting actuating and actuated switch members, and consisting of a fibrous, oil absorbentelement, formed to be 60 guidingly seated in one of said switch members.

" FRANKLIN HOBART. 

